Whole ground corn meal is the entire corn kernel ground up. Corn gluten meal has much of the carbohydrate stripped off to make corn syrup so what you are left with is the gluten of the seed. It is mostly protein.

Cracked corn is made of broken corn kernels that fall through a sifter. Some fully mature corn kernels are small enough to fall through the sifter. Those will sprout and die after they are mowed one time. I wish all weeds did that.

Whether corn meal attracts or repels your ants remains to be seen. If they take a load of corn meal into their mound, the corn meal grows a fungus that kills other fungi. If the ants are the kind that farm organic material to allow it to rot in their mound, the predatory fungus that grows on the corn meal may destroy their food supply. There is a long standing rumor/urban legend that corn grits kills ants. There could be some truth to that rumor that has not been studied. Generally the cessation of synthetic fertilizers and chemicals and start of organic fertilizing means your entire garden gets more in the natural balance. Predators have healthier prey to eat and that attracts more of them to your yard. I had never seen a toad or lizard in my yard until I stopped using chemicals and began with corn meal.